Internal siphon for pressure gauges



July 8, 1941-. B. MGCLELLAND 224%,683

INTERNAL SIPHON FOR PRESSURE GAUGES- F'iled Oct. 8, 1938 Patented July8, i941 7 2,248,686 INTERNAL sirnon roe reassess. canons BertMcClelland, Perkasie, States Gauge Company,

Pa, assignor to United Sellersville, Pa., a cor- (5 Claims.

This invention relates to pressure gauges of the Bourdon type and moreparticularly to such gauges having internal traps or siphons.

When gauges of this kind are employed to measof tubing arranged withinthe casing and connected between the Bourdon tube and gauge inletpassage so as to form a trap. Also, specially formed post or socketmembers provided with cored-out chambers have been used for thispurpose.

However, while internal traps of the kind just mentioned operate in asatisfactory manner, they involve either radical changes in the sizeand/or shape of post or socket members or the trap tubings occupyconsiderable space within the gauge casing. This is especiallydisadvantageous in certain types of gauges where the shape of the socketmember cannot be conveniently modi- V fled and where practically all ofthe available space within the casing is required by the Bourdon springand gauge movement. This is particularly true of gauges of the so-calledback-connected type in which the post or socket is little more than aframe-work for supporting the gauge parts pended claims and and whereinthere is little extra space available within the casing for an extratrap tube.

It is, therefore, a primary object of this invention to provide animproved. pressure gauge havure the pressure of high temperature fluids,such 5 ing an internal trap which does not occupy any as high pressuresteam, the provision of some sort of the space within the casing oralter the shape of a trap, or siphon, as it is sometimes called, has orsize of the post or socket member. been resorted to in order to preventdirect contact More particularly it is an object of this invenof thehigh temperature fluid with the Bourdon tion to provide an improvedinternal trap or spring element. The spring element being formed siphonwhich, while formed directly within a porof thin metal its physicalcharacteristics are, of tion of the post or socket member, so as to notcourse, affected by high temperatures and direct occupy any space withinthe gauge casing, is of contact of the high temperature fluid therewithample capacity to insure its proper operation at is, therefore,undesirable. Also, the spring eleall times. ments are usually joined totheir supporting mem- A St l rt O j of y invention is to p bers bysoldered joints which should be protected vide an improved gauge of theback-connected from the high temperature fluid. type having an internal.trap formed directly Accordingly, it has long been the practice towithin a nipple portion of the post or socket memprovide a trap means,somewhere in the line her so as to not change the size or shape ofleading to the gauge, for collecting a body of the post member.condensed fluid of sufiicient volume to entirely Another object of thisinvention is to provide an an the spring element. This body oi liquidtransimproved gauge construction wherein a trap mits the pressure of thefluid, behind it, to the hamb r i rr ne d en i ly wi h n a ni pl prspring element while at the same time it protects t on of h S cketmember d abo e jo nt the element from direct contact with the heatedbetween the Bourdon spring and socket member. fluid. A still furtherobject of this invention is to pro- Sometimes these traps consist merelyof looped vide an improved gauge construction having a portions in apipe leading to the gauge, i. e., large sized trap chamber together withmeans for the well known pig-ta siphon, but as this arfacilitating thecondensation of high temperature rangement is somewhat objectionablefrom the fluid therein. standpoint of unsightliness, and also is exposedIt is also an object of this invention to provide to damaging blows, ithas also been proposed to an improved pressure gauge embodying aninarrange the trapentirely Within the gauge casing. ternal trap formedwithin the post or socket mem- Several kinds of traps of the latter typehave her which is simple in construction, inexpensive been suggestedwhich include a separate section 31) to make, and positive and efiicientin operation.

The foregoing and other ancillary objects will become apparent from thefollowing detailed description of a preferred embodiment of my inventionwhen considered in connection with the apaccompanying drawing, wherein:

Figure 1 is a front elevation of a gauge emhodying my invention with theouter casing removed to show the interior construction thereof:

Figure 2 is a front view of the post or socket member of the gauge shownin Figure 1; and

Figure 3 is a side elevation of the post or socket member shown inFigure 2.

Referring to Figures 2 and 3, the post or socket member comprises a mainbody 2 from which extend forwardly projecting portions 3 and 4.Extending rearwardly from body portion 2 is a cylindrical nipple 6 whichis machined with flats, at 'Lto provide for wrench connection and isthreaded at its outer end at 8. Nipple portion 1 is drilled or cored-outto form a recess or chamber 9 and this recess extends through the frontof body portion 2, as will be seen from an inspection of Figure 3. Adrilled aperture I I leads into the upper portion of recess 9 for apurpose to be later described.

The front faces of projecting portions 3 and 4 are provided with themachined fiat surfaces I2 and I3, which lie in a common plane andprovide means for attaching a dial or like element to the post or socketmember, such element being attached by screws or rivets received inapertures I4 and It, provided in the surfaces 42 and I3 aforementioned.

Threaded openings I! are provided in the base or socket member as shownin Figure 2 for the purpose of securing the same to a gauge casingstructure in the usual manner. Bosses I8 and I9 receive a movement plate2I, secured thereto by screws 23, which carries the gauge movementmechanism, including a front plate 22, held in spaced relation fromplate 2I by spacing screws 24. A quadrant 25 is pivoted between plates25 and 22 and meshes with a gear carried by shaft 21, the usualhair-spring 26 being provided to compensate for backlash in the parts.Quadrant 26 is connected by means of link 29 to a connecting member 3|carried by the extreme end of a Bourdon tube 32.

The opposite end of the Bourdon tube 32 is received in an elongated slot33 provided in the forwardly projecting portion 4 (see Figures 2 and 3),the usual soldered connection 34 being provided at this point to providea liquid-tight joint.

Leading rearwardly from the recess 33 is a duct 36 which connects with adrilled opening 3 extending upwardly into the front and lower portion ofthe recess 9. The lower end of passage 33 is plugged as shown at 39 (seeFigure 3). A plate 4| is secured over the front of recess 9 in anyconvenient manner, as for example by staking or soldering, as shown at42. If desired, plate 4| may be threaded into the body 2 or any othersure.

The recess 9 can be formed in any convenient manner, but is preferablyobtained by drilling out the nipple portion 6 on a conventional designpost member of the so-called back-connected type. However, this recess 9may obviously be formed by coring-out the nipple member in the initialcasting process. In either event it will be observed that the recess 9is of considerable capacity and also that it is located an appreciabledistance above the lower end of the Bourdon tube 32. Furthermore, therecess is made as large as possible without weakening the nipple so thatthe nipple wall forming the recess is relatively thin.

hen the gauge is connected to a steam line by the threaded portion 8,and with the gauge parts in their proper vertical position as shown inFigure 1, the steam enters through the relatively small aperture II and,due to the expansion thereof into the large chamber 9, is condensed.Condensation is also facilitated by cooling of the steam through thethin nipple wall. This condensate eventually fills chamber 9, ducts 38,36 and the lower part of Bourdon tube 32 to a level determined by theheight of the smallsized opening I i, see dot-dash lines Figures 1 and2. The chamber 9 is preferably large enough to hold a VOIUIlle of liquidsufficient to entirely fill that part of the Bourdon spring above theaforementioned level. Accordingly, when the steam pressure, acting uponthe liquid, forces the same into the Bourdon tube, the liquid willentirely fill it, and yet, at the same time, all of the liquid will nothave been displaced from the chamber 9. Therefore, it will be seen thatthe lower por-- tion of Bourdon tube 32, especially around the solderedconnection 3 1, will at all times be covered up by the condensed fluid.Also, the hot steam, or other high temperature fluid, the pressure ofwhich is being measured, cannot come into direct contact with theBourdon tube 32.

Thus I have provided an improved Bourdon pressure gauge having aninternal trap of relatively large capacity without in any way alteringthe shape of the post or socket member. The drilling out of the opening9 in no way detracts from the structural strength of the post or socketmember 2 since it is substantially all done within the extended nippleportion 6 and a suihcient wall thickness on this nipple portion can beleft in order to insure adequate strength in this portion for supportingthe gauge on a steam pipe or other equivalent means leading from asource of liquid under fluid pressure. Yet, at the same time, the wallthickness of the trap chamber can be reduced sufi'dciently to aid incondensation, as above explained, and which is further augmented by theincreased internal condensing surface provided. The trap, since it isentirely enclosed within the post or socket member, does not occupy anyof the space within the gauge casing. This is of considerable importancein gauges of the so-callcd back-connected type in which the surroundingcasing member is usually just large enough to nicely enclose thecircular-shaped Bourdon spring 32, leaving little, if any, room withinthe casing for an additional tube or trap element, such as is frequentlyused to provide a siphon or trap as has been previously mentioned in theforegoing part of this specification.

The drilling out of opening 9 or its formation in the casting process isa simple and inexpensive procedure and the provision of the closingplate 4| by means of staking or possibly by threading or soldering atpoint 42 is likewise a step which involves little labor or addedexpense.

Accordingly, it will be seen that I have provided an extremely simpletype of internal trap which is particularly well adapted for gauges ofthe back-connected type but may also be applied to post or socketmembers of other types. My improved construction provides a trap ofadequate and sufiicient volume, located well above the Bourdon springconnection to Protect the soldered joint, and designed to insurecondensation of the liquid by expansion thereinto through tically allkinds and descriptions.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theapare therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. A pressure gauge, comprising, a socket tional area as compared tothat of said chamber, member having a body section and a threadedwhereby fluid under pressure passing through nipple extending laterallyfrom said body section, said passage is caused to expand and condense aBourdon spring secured to said body at a point Within said chamber.below said nipple and including a part extending a 5. A pressure gauge,comprising, a socket upwardly above said nipple, said nipple beingmember having a body section and a threaded formed to provide anenlarged chamber, said nipple extending rearwardly therefrom, saidnipbody being provided with a passage connecting ple being hollowed outto form a recess extendthe lower portion of said chamber to said Bouringfrom the front of said body to a point addon spring, and said nipplebeing provided with a, H) jacent the rear of said nipple, means securedto passage leading to the upper portion of said said body for closingsaid recess at the front of chamber for connecting said chamber to asource said body, a Bourdon spring secured to said body of fluid underpressure. at a point materially below said recess, said body 2.Apressure gauge, comprising, asocket membeing provided with a passageconnecting said ber having a body section and a threaded nipple I ospring and said recess, and said nipple being proextending therefrom atright angles to said body vided with an inlet passage to the upperportion section, a Bourdon spring secured to said body of said recess.at a point below said nipple and including a part 6. A pressure gauge,comprising, a socket memextending upwardly above said nipple, saidnipple ber having a rearwardly extending nipple therebeing formed toprovide an enlarged chamber, :0 on, a Bourdon spring mounted on saidsocket at a said body being provided with a passage connectpoint belowsaid nipple, said socket member being ing the lower portion of saidchamber to said p vid d wi a bore extending t sa n pp Bourdon spring,and said nipple being provided to a point adjacent its outer end, saidbore being with a passage adjacent the upper portion of but slightlysmaller than the outside diameter of said chamber for connecting saidchamber to a said nipple to t r y Provide an enlarged p source of fluidund r ressure. chamber, having relatively thin walls formed by 3. Apressure gauge comprising the combinasaid nipple, said body beingprovided with a tion set forth in claim 2, wherein said enlarged passageconnecting said chamber to said Bourdon chamber has a capacityapproximately equal to spring, and the outer end of said nipple beingthat of the part of said Bourdon spring which ex- 139 provided with apassage adjacent the upper portends above said nipple. tion of thechamber for connecting said cham- 4. A pressure gauge, comprising thecombinaber to a source of fluid under pressure. tion set forth in claim2, wherein said passage means in said nipple is of restricted cross-sec-BERT MCCLELLAND.

